Unit 1 Test Corrections

What is evolution?

A change in a population or species gene pool over time. The more genetic variation, or change, a species has, the more likely that at least some organisms will have genetic traits that help them survive. Therefore, evolution is an important process to prevent extinction.

Graphs are a great way to ________ data.

Analyze. Analysis is the process of looking for patterns in the data that you collected during your experiment. Graphs are a great way to look at patterns or typical values in the data. For example, this graph clearly shows how the population changes over time.

A student studies the gathering of frogs at the end of a pond. She has collected data and formed graphs. What is her next step in the process of scientific inquiry?

Form a conclusion. Graphs are used to analyze data. Once you analyze the data and look for patterns, you can develop a conclusion that answers your research question.

Keeping humans' internal body temperature stable is a great example of ________________. When an individual is healthy, his or her body temperature stays at an average temperature of 98.6 degrees Fahrenheit (mean body temperature in humans). If the temperature gets too high or too low, the body can control temperature by making or releasing heat.

Homeostasis. Homeostasis literally means "same state." It is important for all living things to find ways to keep their internal conditions, or state, stable. For example, our body's regulates its own internal body temperature, as well as our blood sugar, blood pressure, and heart rate, among other things.

Which of the following is a scientific hypothesis?

If we treat COVID-19 patients with steroids, they will improve, because steroids will help to reduce inflammation. Hypotheses should always be in the format if...then...because. The because is the most important part, because it makes sure that you are setting up your experiment based on what you already know about the topic. It makes for a smarter experiment. If we treat COVID-19 patients with steroids, [then] they will improve, because steroids will help to reduce inflammation.

Which type of graph is shown in the picture?

Line graph. Line graphs are very useful for showing the change in a variable over time. They are used to look for patterns in continuous data--data that have an infinite, or almost infinite, spread of values. In this case the line graph shows the change in the bacterial population over time.

What is the dependent variable in this experiment?

Mass of the plant. The dependent variable is the outcome in an experiment. It's what you measure at the end. In this experiment, a farmer gave plants different amounts of fertilizer and measured their mass to see if the fertilizer affected their growth. You can also think of this in terms of which makes sense--Would you experiment to see if fertilizer affects the mass of plants? Yes. Would you experiment to see if the mass of plants affect how much fertilizer you give them? No.

When does the bacterial population reach its peak?

September. A peak is the highest point--like the peak of a mountain. This graph shows that the bacterial population reached it's highest point, or max, in September.

The control group was ...

The Walmart tomato plants. The control group is the group in an experiment that receives nothing, or the "usual." In this case, the Walmart tomato plants represent regular, store-bought tomato plants. Therefore, they are the control group. Remember that we always compare experimental and control groups in an experiment to see if the outcome is different between groups. Control groups are NOT the same as controlled variables!

One of the controlled variables was ...

The amount of water given to each tomato. Controlled variables are the variables (things) that you intentionally keep the same between the groups so that they don't interfere with your results. Because the amount of water can also affect how well the tomatoes grow, Mr. Golden had to control, or keep the amount of water the same, between the 2 groups.

What is the conclusion of this experiment?

The heirloom and Walmart plants produced about the same amount of tomatoes. The conclusion is the answer to the research question, based upon your analysis of the data. In this case, since the two groups produced 11 and 12 tomatoes, they essentially produced the same amount. The heirloom tomatoes did not do dramatically better, as one might have thought they would.

The experimental group was ...

The heirloom tomatoes. The experimental group is the group that receives whatever you are testing out, or experimenting with. In this case, Mr. Golden was testing to see whether the heirloom tomato plants would, in fact, produces more tomatoes than the everyday Walmart tomato plants. Therefore, the heirloom tomato plants are the experimental group.

The factor being changed in a controlled experiment is ...

The independent variable. Remember "I can change" for independent variable. The independent variable is the one thing that the investigator chooses to be different between groups at the beginning of the experiment. The scientist is testing the independent variable vs. a control, or "competitor," to see if it really makes a difference in the outcome.

The dependent variable was ...

The number of tomatoes growing on the plants. The dependent variable is the outcome. It's the thing you measure at the end of the experiment to see if the independent variable actually made a difference. Therefore, the dependent variable "depends" on the independent variable. In this case, Mr. Golden counted the number of number of tomatoes that grew to see if the heirloom tomatoes did better, the same, or worse than the Walmart tomatoes.

The independent variable was ...

The type of tomato. The independent variable is the variable that the investigator chooses to change or test out. Think "I can change." You can also think of it as the one thing that is intentionally different about the groups at the beginning. In this case, Mr. Golden was testing to see whether the Walmart brand or heirloom tomatoes were better. Therefore, the type of tomato was the independent variable.

What is the independent variable in this experiment?

Time, or month of the year. Remember DRY - MIX. The independent variable (I) is placed on the X axis. The dependent variable (D) is placed on the Y axis.

Tina conducted an experiment to test her hypothesis. Her hypothesis was that by crushing aspirin and putting it into potting soil increases the growth rate of tomato plants. The results of the experiment show that there was no significant difference in the growth rates between the control and the experimental groups. What should Tina do with the results of this experiment?

Use the results to look at the situation in a new way and reapply it in a future investigation. Remember that the scientific process/inquiry is a cycle. It does not stop with your conclusion. Tina concluded that there was not a significant difference in growth between her groups. This conclusion should lead her to ask new questions about what other factors might affect growth.

What is genetic material?

molecules that carry the information for how we are built; examples include DNA and RNA.

What is reproduction?

producing offspring; producing more of a population or species. Species need reproduction so that they don't die out over time.

What is energy/metabolism?

the ability to do work; in living things, this is often the ability to perform daily activities and usually requires eating or producing their own food; Metabolism is the sum of all of the chemical reactions in a living thing--it takes energy to keep us alive. Living things, therefore, have to obtain and use energy.